Kaletsky Rachel, Moore Rebecca S, Sengupta Titas, Seto Renee, Ceballos-Llera Borja, Murphy Coleen T
Department of Molecular Biology, Princeton University, Princeton, United States.
LSI Genomics, Princeton University, Princeton, United States.
Elife. 2025 May 15;14:RP105673. doi: 10.7554/eLife.105673.
Bacteria are food, and worms are naturally attracted to many bacteria, including pathogenic , preferring PA14 over laboratory (OP50). Despite this natural attraction to PA14, prior PA14 exposure causes the worms to instead avoid PA14. This behavioral switch can happen quickly - even within the duration of the choice assay. We show that accurate assessment of the animals' true first choice requires the use of a paralytic (azide) to trap the worms at their initial choice, preventing the switch from attraction to avoidance of PA14 within the assay period. We previously discovered that exposure of to 25°C plate-grown PA14 at 20°C for 24 hr not only leads to PA14 avoidance, but also to four generations of naïve progeny avoiding PA14, while other PA14 paradigms only cause P0 and/or F1 avoidance. We also showed that the transgenerational (P0-F4) epigenetic avoidance is mediated by P11, a small RNA produced by PA14. P11 is both necessary and sufficient for TEI of learned avoidance. P11 is highly expressed in our standard growth conditions (25°C on surfaces), but not in other conditions, suggesting that the reported failure to observe F2-F4 avoidance is likely due to the absence of P11 expression in PA14 in the experimenters' growth conditions. Additionally, we tested ~35 genes for involvement in TEI of learned pathogen avoidance. The conservation of multiple components of this sRNA TEI mechanism across strains and in multiple species suggests that this TEI behavior is likely to be physiologically important in wild conditions.
细菌是食物，蠕虫天然会被许多细菌吸引，包括致病菌，相较于实验室用菌（OP50），它们更喜欢PA14。尽管对PA14有这种天然的吸引力，但先前接触过PA14会使蠕虫转而避开PA14。这种行为转变可能很快发生——甚至在选择试验期间内。我们表明，要准确评估动物真正的第一选择，需要使用麻痹剂（叠氮化物）在其初始选择时困住蠕虫，以防止在试验期间从对PA14的吸引转变为避开。我们之前发现，在20°C下将线虫暴露于25°C平板培养的PA14中24小时，不仅会导致线虫避开PA14，还会使四代未接触过的后代也避开PA14，而其他PA14实验模式只会导致P0代和/或F1代避开。我们还表明，跨代（P0 - F4）的表观遗传避开是由PA14产生的一种小RNA P11介导的。P11对于习得性避开的跨代遗传诱导既是必要的也是充分的。P11在我们的标准生长条件（25°C表面培养）下高度表达，但在其他条件下不表达，这表明报道中未能观察到F2 - F4代避开现象可能是由于实验者生长条件下PA14中缺乏P11表达。此外，我们测试了约35个基因参与习得性病原体避开的跨代遗传诱导情况。这种小RNA跨代遗传诱导机制的多个组成部分在不同线虫品系和多个线虫物种中的保守性表明，这种跨代遗传诱导行为在野生条件下可能具有重要的生理意义。
